chapter 21

• CO2 - from heart to lung
• O2 - from lung to heart

• O2 in blood to body cells
• CO2 blood back to heart

carry blood away from the heart

return blood to the heart

interconnect smallest arteries with smallest veins - thin walls- exchange vessels

serous membrane lines pericardial cavity

epicardium

parietal layer + connective tissue

cardiac muscle tissue

internal surface, simple squamous epithelium continuous with lining of blood vessels

cells - small, interconnected with cell junctions (intercalcated discs) and gap junctions: ions and small moulecules pass

Dense C.t, btw atria and ventricles, also form rings to stabalize heart valves, distribute force of contraction

• Receiving chambers
• right atrium - blood from body
• left atrium - blood from lung

• receive venous blood
• pump only to ventricles
• thin muscular distensible wall

• discharging chambers
• right ventricles - blood to lungs
• left ventricles - blood to body

• send out arterial blood to pulmonary and systemic circulatory systems
• have thick muscular walls

• receives blood from superior and inferior vena cava
• atrial walls - contain pectinate muscles
• coronary veins - returns blood from coronary sinus
• foramen ovale (an opening during embroynic development) penetrates interatrial septum and closes after birth and became fossa ovalis

• Right atrium to right ventricle through atrioventricular valve (AV valve)
• opening - bounded by 3 cusps of fibrous c.t, braced by chordae tendineae - connected to papillary muscles

• blood leave RV to pulmonary trunk after passing through pulmonary semilunar valve
• trabeculae carneae - series of irregular muscular folds in internal surface of ventricle
• moderator band - extends from interventricular septum ( separates 2 ventricles )

• left and right pulmonary veins
• auricle
• left atrioventricular valve (bicuspid)

• aortic semilunar valve
• ascending aorta

• allow blood flow in only one direction
• 4 valves

• heartbeat to heartbeat
• systole - contraction
• diastole - relaxation
• contractions controlled by conducting cells

• Pwave - atrial depolarization (atrial contractions)
• QRS complex - ventrical depolarization (ventricular contractions)
• Twave - ventricular repolarization (resting of ventricles)